Heat exchanger assemblies for electronic devices and related methods

ABSTRACT

Heat exchanger assemblies for electronic devices and related methods are disclosed. A heat exchanger assembly may include a heat transfer body that has a face that forms open passageways, and a cover structure attached to the heat transfer body that encloses the open passageways, thereby forming enclosed fluid conduits. Heat exchanger assemblies as described herein may be thermally coupled to a center waveguide section of a spatial power-combining device. Related methods include forming open passageways by selectively removing material from a face of a heat transfer body. Multiple heat transfer bodies may be formed simultaneously by forming multiple groups or patterns of open passageways across a larger area of a heat transfer body material, and subsequently singulating the heat transfer body material into multiple heat transfer bodies. Cover structures as previously described may be formed on the heat transfer bodies before or after singulation.

PRIORITY APPLICATION

This application claims the benefit of provisional patent applicationSer. No. 62/714,878, filed Aug. 6, 2018, the disclosure of which ishereby incorporated herein by reference in its entirety.

RELATED APPLICATION

The present application is related to U.S. patent application Ser. No.16/288,735 filed on Feb. 28, 2019 and published as U.S. PatentApplication Publication No. 2020/0041209, entitled “HEAT EXCHANGERASSEMBLIES FOR ELECTRONIC DEVICES,” which is incorporated herein byreference in its entirety.

FIELD OF THE DISCLOSURE

The disclosure relates generally to heat exchanger assemblies forelectronic devices and, more particularly, to heat exchanger assembliesfor spatial power-combining devices and related methods.

BACKGROUND

Spatial power-combining devices, such as a Qorvo® Spatium® spatialpower-combining device, are used for broadband radio frequency poweramplification in commercial and defense communications, radar,electronic warfare, satellite, and various other communication systems.Spatial power-combining techniques are implemented by combiningbroadband signals from a number of amplifiers to provide output powerswith high efficiencies and operating frequencies. One example of aspatial power-combining device utilizes a plurality of solid-stateamplifier assemblies that form a coaxial waveguide to amplify anelectromagnetic signal. Each amplifier assembly may include an inputantenna structure, an amplifier, and an output antenna structure. Whenthe amplifier assemblies are combined to form the coaxial waveguide, theinput antenna structures may form an input antipodal antenna array, andthe output antenna structures may form an output antipodal antennaarray.

In operation, an electromagnetic signal is passed through an input portto an input coaxial waveguide section of the spatial power-combiningdevice. The input coaxial waveguide section distributes theelectromagnetic signal to be split across the input antipodal antennaarray. The amplifiers receive the split signals and in turn transmitamplified split signals across the output antipodal antenna array. Theoutput antipodal antenna array and an output coaxial waveguide sectioncombine the amplified split signals to form an amplified electromagneticsignal that is passed to an output port of the spatial power-combiningdevice.

Antenna structures for spatial power-combining devices typically includean antenna signal conductor and an antenna ground conductor deposited onopposite sides of a substrate, such as a printed circuit board. The sizeof the antenna structures are related to an operating frequency of thespatial power-combining device. For example, the size of the inputantenna structure is related to the frequency of energy that can beefficiently received, and the size of the output antenna structure isrelated to the frequency of energy that can be efficiently transmitted.Overall sizes of spatial power-combining devices typically scale largeror smaller depending on desired operating frequency ranges. Additionalsize and structural considerations for spatial power-combining devicesinvolve providing good thermal management for heat generated duringamplification.

The art continues to seek improved spatial power-combining deviceshaving improved thermal management and good operating performance whilebeing capable of overcoming challenges associated with conventionaldevices.

SUMMARY

Aspects disclosed herein relate to heat exchanger assemblies forelectronic devices and, more particularly, to heat exchanger assembliesfor spatial power-combining devices. According to embodiments disclosedherein, a heat exchanger assembly includes a heat transfer body that hasa face that forms open passageways. A cover structure may be attached tothe heat transfer body in a manner to enclose the open passageways,thereby forming a heat exchanger assembly that includes enclosed fluidconduits. In this regard, the enclosed fluid conduits may form complexand intricate patterns within the heat exchanger assembly that aretailored to the heat requirements of a particular application. Incertain embodiments, heat exchanger assemblies as described herein arethermally coupled to a center waveguide section of a spatialpower-combining device. The enclosed fluid conduits may be tailoredbased on locations of amplifiers within the center waveguide section toprovide improved thermal operation of the spatial power-combiningdevice. A method of manufacturing a heat exchanger assembly includesforming open passageways on a face of a heat transfer body andsubsequently enclosing the open passageways with a cover structure. Openpassageways may be formed by selectively removing material from a faceof the heat transfer body. Multiple heat transfer bodies may be formedsimultaneously by providing multiple groups or patterns of openpassageways across a larger area of a heat transfer body material, andsubsequently singulating the heat transfer body material into multipleheat transfer bodies. Cover structures as previously described may beformed on the heat transfer bodies before or after singulation

In one aspect, a method for fabricating a heat exchanger assembly for aspatial power-combing device comprises: providing a heat transfer bodycomprising a first face and a second face that opposes the first face;forming a plurality of open passageways on the first face; and attachinga cover structure to the first face to form the heat exchanger assembly,wherein the cover structure and the plurality of open passageways of theheat transfer body form a plurality of enclosed fluid conduits withinthe heat exchanger assembly. In certain embodiments, forming theplurality of open passageways on the first face comprises selectivelyremoving portions of the heat transfer body on the first face. Incertain embodiments, selectively removing portions of the heat transferbody on the first face comprises at least one of chemical etching, lasermachining, rotary table machining, micromachining, or multi-axismachining. In certain embodiments, selectively removing portions of theheat transfer body on the first face comprises applying a chemicaletchant through a mask on the first face. In certain embodiments,attaching the cover structure to the first face comprises at least oneof soldering, brazing, welding, or bonding with epoxy. The heatexchanger assembly may comprise a planar shape. In certain embodiments,the method further comprises forming the heat exchanger assembly into anon-planar shape. The non-planar shape may comprise a cylindrical shape.In certain embodiments, the cover structure is attached to the firstface before forming the heat exchanger assembly into the non-planarshape. In certain embodiments, the plurality of enclosed fluid conduitsare arranged in different concentrations within different areas of theheat exchanger assembly. At least one enclosed fluid conduit of theplurality of enclosed fluid conduits may be arranged with a differentdiameter than other enclosed fluid conduits of the plurality of enclosedfluid conduits. At least one enclosed fluid conduit of the plurality ofenclosed fluid conduits may comprise alternating concave and convexcurved portions. At least one enclosed fluid conduit of the plurality ofenclosed fluid conduits may be configured to split into multipleenclosed fluid conduits between a first edge and a second edge of theheat transfer body. At least one enclosed fluid conduit of the pluralityof enclosed fluid conduits may transverse the heat exchanger assembly ina linear manner between two radially arranged enclosed fluid conduits ofthe plurality of enclosed fluid conduits.

In another aspect, a method comprises: providing a heat transfer bodymaterial; forming a plurality of open passageway patterns on a firstface of the heat transfer body material; attaching a cover structurematerial to the first face, wherein the cover structure material and theplurality of open passageway patterns form a plurality of enclosed fluidconduits; and separating the heat transfer body material and the coverstructure material into a plurality of heat exchanger assemblies,wherein each heat exchanger assembly of the plurality of heat exchangerassemblies comprises a heat transfer body, a cover structure, and aplurality of enclosed fluid conduits. In certain embodiments, formingthe plurality of open passageway patterns on the first face comprisesselectively removing portions of the heat transfer body material on thefirst face. In certain embodiments, selectively removing portions of theheat transfer body material on the first face comprises at least one ofchemical etching, laser machining, rotary table machining,micromachining, or multi-axis machining. In certain embodiments,selectively removing portions of the heat transfer body material on thefirst face comprises applying a chemical etchant through a mask on thefirst face. The method may further comprise forming each heat exchangerassembly of the plurality of heat exchanger assemblies into a non-planarshape. The non-planar shape may comprise a cylindrical shape.

In another aspect, a method comprises: providing a heat transfer bodymaterial; forming a plurality of open passageway patterns on a firstface of the heat transfer body material; and separating the heattransfer body material into a plurality of heat transfer bodies, whereineach heat transfer body of the plurality of heat transfer bodiescomprises a separate open passageway pattern of the plurality of openpassageway patterns. In certain embodiments, the method furthercomprises attaching a separate cover structure to each heat transferbody of the plurality of heat transfer bodies to form a plurality ofheat exchanger assemblies, wherein the cover structure and the openpassageway pattern of each heat exchanger assembly forms a plurality ofenclosed fluid conduits. In certain embodiments, the method furthercomprises forming each heat exchanger assembly of the plurality of heatexchanger assemblies into a non-planar shape. The non-planar shape maycomprise a cylindrical shape. In certain embodiments, forming theplurality of open passageway patterns on the first face comprisesselectively removing portions of the heat transfer body material on thefirst face. In certain embodiments, selectively removing portions of theheat transfer body material on the first face comprises at least one ofchemical etching, laser machining, rotary table machining,micromachining, or multi-axis machining. In certain embodiments,selectively removing portions of the heat transfer body material on thefirst face comprises applying a chemical etchant through a mask on thefirst face.

In another aspect, any of the foregoing aspects, and/or various separateaspects and features as described herein, may be combined for additionaladvantage. Any of the various features and elements as disclosed hereinmay be combined with one or more other disclosed features and elementsunless indicated to the contrary herein.

Those skilled in the art will appreciate the scope of the presentdisclosure and realize additional aspects thereof after reading thefollowing detailed description of the preferred embodiments inassociation with the accompanying drawing figures.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

The accompanying drawing figures incorporated in and forming a part ofthis specification illustrate several aspects of the disclosure, andtogether with the description serve to explain the principles of thedisclosure.

FIG. 1 is a partially-exploded perspective view of a spatialpower-combining device.

FIG. 2 is a perspective view of the assembled spatial power-combiningdevice of FIG. 1 with a heat exchanger assembly according to embodimentsdisclosed herein.

FIG. 3 is a perspective view of a heat transfer body according toembodiments disclosed herein.

FIG. 4 is a perspective view of a cover structure that is configured tocover the heat transfer body of FIG. 3 according to embodimentsdisclosed herein.

FIG. 5A is a perspective view of an assembled heat exchanger assemblythat includes the heat transfer body of FIG. 3 and the cover structureof FIG. 4.

FIG. 5B is a perspective view of the heat exchanger assembly of FIG. 5Awith the cover structure shown as transparent for illustrative purposes.

FIG. 6 is top view of a heat transfer body material on which a pluralityof heat transfer bodies will be formed according to embodimentsdisclosed herein.

FIG. 7 is a top view illustrating formation of cover structures over theheat transfer body material of FIG. 6.

FIG. 8A is a top view of an individual heat exchanger assembly of FIG. 7after singulation.

FIG. 8B is a top view of the heat exchanger assembly of FIG. 8A with thecover structure shown as transparent for illustrative purposes.

FIG. 9A is a top view of a heat transfer body with a differentconfiguration of a plurality of open passageways according toembodiments disclosed herein.

FIG. 9B is a perspective view of the heat transfer body of FIG. 9A thathas been formed into a non-planar shape.

FIG. 10A is a perspective view of a heat transfer body with a differentconfiguration of a plurality of open passageways according toembodiments disclosed herein.

FIG. 10B is a perspective view of the heat transfer body of FIG. 10Athat has been formed into a non-planar shape.

DETAILED DESCRIPTION

The embodiments set forth below represent the necessary information toenable those skilled in the art to practice the embodiments andillustrate the best mode of practicing the embodiments. Upon reading thefollowing description in light of the accompanying drawing figures,those skilled in the art will understand the concepts of the disclosureand will recognize applications of these concepts not particularlyaddressed herein. It should be understood that these concepts andapplications fall within the scope of the disclosure and theaccompanying claims.

It will be understood that, although the terms first, second, etc. maybe used herein to describe various elements, these elements should notbe limited by these terms. These terms are only used to distinguish oneelement from another. For example, a first element could be termed asecond element, and, similarly, a second element could be termed a firstelement, without departing from the scope of the present disclosure. Asused herein, the term “and/or” includes any and all combinations of oneor more of the associated listed items.

It will be understood that when an element such as a layer, region, orsubstrate is referred to as being “on” or extending “onto” anotherelement, it can be directly on or extend directly onto the other elementor intervening elements may also be present. In contrast, when anelement is referred to as being “directly on” or extending “directlyonto” another element, there are no intervening elements present.Likewise, it will be understood that when an element such as a layer,region, or substrate is referred to as being “over” or extending “over”another element, it can be directly over or extend directly over theother element or intervening elements may also be present. In contrast,when an element is referred to as being “directly over” or extending“directly over” another element, there are no intervening elementspresent. It will also be understood that when an element is referred toas being “connected” or “coupled” to another element, it can be directlyconnected or coupled to the other element or intervening elements may bepresent. In contrast, when an element is referred to as being “directlyconnected” or “directly coupled” to another element, there are nointervening elements present.

Relative terms such as “below” or “above” or “upper” or “lower” or“horizontal” or “vertical” may be used herein to describe a relationshipof one element, layer, or region to another element, layer, or region asillustrated in the Figures. It will be understood that these terms andthose discussed above are intended to encompass different orientationsof the device in addition to the orientation depicted in the Figures.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the disclosure.As used herein, the singular forms “a,” “an,” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprises,”“comprising,” “includes,” and/or “including” when used herein specifythe presence of stated features, integers, steps, operations, elements,and/or components, but do not preclude the presence or addition of oneor more other features, integers, steps, operations, elements,components, and/or groups thereof.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which this disclosure belongs. It willbe further understood that terms used herein should be interpreted ashaving a meaning that is consistent with their meaning in the context ofthis specification and the relevant art and will not be interpreted inan idealized or overly formal sense unless expressly so defined herein.

Aspects disclosed herein relate to heat exchanger assemblies forelectronic devices and, more particularly, to heat exchanger assembliesfor spatial power-combining devices. According to embodiments disclosedherein, a heat exchanger assembly includes a heat transfer body that hasa face that forms open passageways. A cover structure may be attached tothe heat transfer body in a manner to enclose the open passageways,thereby forming a heat exchanger assembly that includes enclosed fluidconduits. In this regard, the enclosed fluid conduits may form complexand intricate patterns within the heat exchanger assembly that aretailored to the heat requirements of a particular application. Incertain embodiments, heat exchanger assemblies as described herein arethermally coupled to a center waveguide section of a spatialpower-combining device. The enclosed fluid conduits may be tailoredbased on locations of amplifiers within the center waveguide section toprovide reduced operating temperature of the spatial power-combiningdevice. A method of manufacturing a heat exchanger assembly includesforming open passageways on a face of a heat transfer body andsubsequently enclosing the open passageways with a cover structure. Openpassageways may be formed by selectively removing material from a faceof the heat transfer body. Multiple heat transfer bodies may be formedsimultaneously by providing multiple groups or patterns of openpassageways across a larger area of a heat transfer body material, andsubsequently singulating the heat transfer body material into multipleheat transfer bodies. Cover structures as previously described may beformed on the heat transfer bodies before or after singulation.

The embodiments are particularly adapted to spatial power-combiningdevices that operate at microwave frequencies such as, by way ofnon-limiting example, energy between about 300 megahertz (MHz) (100centimeters (cm) wavelength) and 300 gigahertz (GHz) (0.1 cmwavelength). Additionally, embodiments may comprise operating frequencyranges that extend above microwave frequencies. A spatialpower-combining device may operate within one or more common radar bandsincluding, but not limited to S-band, C-band, X-band, Ku-band, K-band,Ka-band, and Q-band. In some embodiments, by way of non-limitingexamples, the operating frequency range includes an operating bandwidthspread of 2 GHz to 20 GHz.

A spatial power-combining device generally includes a plurality ofamplifier assemblies, and each amplifier assembly is an individualsignal path and includes an amplifier connected to an input antennastructure and an output antenna structure. An input coaxial waveguide isconfigured to provide a signal concurrently to each input antennastructure, and an output coaxial waveguide is configured to concurrentlycombine amplified signals from each output antenna structure. Theplurality of amplifier assemblies are typically arranged coaxially abouta center axis. Accordingly, the spatial power-combining device isconfigured to split, amplify, and combine an electromagnetic signal.

FIG. 1 is a partially-exploded perspective view of a spatialpower-combining device 10. The spatial power-combining device 10comprises an input port 12 and an input coaxial waveguide section 14.The input coaxial waveguide section 14 provides a broadband transitionfrom the input port 12 to a center waveguide section 16. Electrically,the input coaxial waveguide section 14 provides broadband impedancematching from an impedance Z_(p1) of the input port 12 to an impedanceZ_(c) of the center waveguide section 16. The input coaxial waveguidesection 14 includes an inner conductor 18 and an outer conductor 20 thatradially surrounds the inner conductor 18, thereby forming an openingtherebetween. Outer surfaces of the inner conductor 18 and an innersurface of the outer conductor 20 have gradually changed profilesconfigured to minimize the impedance mismatch from the input port 12 tothe center waveguide section 16.

The center waveguide section 16 comprises a plurality of amplifierassemblies 22 arranged radially around a center axis of the spatialpower-combining device 10. In certain embodiments, a center post 24 isprovided at the center axis for mechanical support and the plurality ofamplifier assemblies 22 may be positioned circumferentially around thecenter post 24. In other embodiments, the center post 24 may be omitted.In FIG. 1, the center post 24 is illustrated in an exploded manner. Eachamplifier assembly 22 comprises a body structure 26 having apredetermined wedge-shaped cross-section, an inner surface 28, and anarcuate outer surface 30. When the amplifier assemblies 22 arecollectively assembled radially about the center axis, they form thecenter waveguide section 16 with a generally cylindrical shape; however,other shapes are possible, such as rectangular, oval, or other geometricshapes.

The spatial power-combining device 10 also comprises an output coaxialwaveguide section 32 and an output port 34. The input port 12 and theoutput port 34 may comprise any of a field-replaceable Subminiature A(SMA) connector, a super SMA connector, a type N connector, a type Kconnector, a WR28 connector, other coaxial to waveguide transitionconnectors, or any other suitable coaxial or waveguide connectors. Inembodiments where the operating frequency range includes a frequency ofat least 18 GHz, the output port 34 may comprise a waveguide outputport, such as a WR28 or other sized waveguide. The output coaxialwaveguide section 32 provides a broadband transition from the centerwaveguide section 16 to the output port 34. Electrically, the outputcoaxial waveguide section 32 provides broadband impedance matching fromthe impedance Z_(c) of the center waveguide section 16 to an impedanceZ_(p2) of the output port 34. The output coaxial waveguide section 32includes an inner conductor 36 and an outer conductor 38 that radiallysurrounds the inner conductor 36, thereby forming an openingtherebetween. Outer surfaces of the inner conductor 36 and an innersurface of the outer conductor 38 have gradually changed profilesconfigured to minimize the impedance mismatch from the output port 34 tothe center waveguide section 16. In certain embodiments, a pin 40connects between the input port 12 and the input coaxial waveguidesection 14, and a pin 42 connects between the output port 34 and theoutput coaxial waveguide section 32. In certain embodiments, the centerpost 24 connects with the inner conductors 18, 36 by way of screws 44,46 on opposite ends of the center post 24. The center post 24 isprovided for simplifying mechanical connections, may have other than acylindrical shape, or may be omitted altogether.

Each amplifier assembly 22 comprises an input antenna structure 48 andan output antenna structure 50, both of which are coupled to anamplifier 52. In some embodiments, the amplifier 52 comprises amonolithic microwave integrated circuit (MMIC) amplifier. A MMIC may bea solid-state gallium nitride (GaN) based MMIC. A GaN MMIC deviceprovides high power density and bandwidth, and a spatial power-combiningdevice may combine power from a plurality of GaN MMICs efficiently in asingle step to minimize combining loss.

In operation, an input signal 54 is propagated from the input port 12 tothe input coaxial waveguide section 14, where it radiates between theinner conductor 18 and the outer conductor 20 and concurrently providesthe input signal 54 to the center waveguide section 16. A plurality ofinput antenna structures 48 of the plurality of amplifier assemblies 22collectively form an input antenna array 56. The input antenna array 56couples the input signal 54 from the input coaxial waveguide section 14,distributing the input signal 54 substantially evenly to each one of theamplifier assemblies 22. Each input antenna structure 48 receives asignal portion of the input signal 54 and communicates the signalportion to the amplifier 52. The amplifier 52 amplifies the signalportion of the input signal 54 to generate an amplified signal portionthat is then transmitted from the amplifier 52 to the output antennastructure 50. A plurality of output antenna structures 50 forms anoutput antenna array 62 that operates to provide the amplified signalportions to be concurrently combined inside the opening of the outputcoaxial waveguide section 32 to form an amplified output signal 54_(AMP), which is then propagated through the output coaxial waveguidesection 32 to the output port 34.

The spatial power-combining device 10 is typically utilized for highpower-combining applications. Accordingly, the amplifier 52 in each ofthe amplifier assemblies 22 is configured for high power amplification,and may therefore generate a high amount of heat. If the operatingtemperature of each amplifier 52 increases too much, the performance andlifetime of each amplifier 52 may suffer. As previously described, theplurality of amplifier assemblies 22 form the center waveguide section16. In this regard, thermal management is needed to effectivelydissipate heat in and around the center waveguide section 16.Accordingly, the body structure 26 of each amplifier assembly 22 maytypically comprise a highly thermally conductive material, such ascopper (Cu), aluminum (Al), or alloys thereof that are configured todissipate enough heat from the amplifier 52 to maintain a suitably lowoperating temperature. In addition to highly thermally conductivemetals, the body structure 26 may comprise highly thermally conductivepolymers and ceramics, including graphite or graphene, or other highlythermally conductive materials.

FIG. 2 is a perspective view of the assembled spatial power-combiningdevice 10 of FIG. 1 with a heat exchanger assembly 64 according toembodiments disclosed herein. In certain embodiments, the heat exchangerassembly 64 is thermally coupled to the center waveguide section 16,which is obscured from view by the heat exchanger assembly 64 in FIG. 2.In particular, the heat exchanger assembly 64 may be thermally coupledto the arcuate outer surface (30 of FIG. 1) of each amplifier assembly(22 of FIG. 1) to further dissipate or transfer heat away from eachamplifier (52 of FIG. 1). As illustrated in FIG. 2, the heat exchangerassembly 64 is registered with the center waveguide section 16. In thismanner, the heat exchanger assembly 64 is arranged between the inputport 12 and the output port 34. The heat exchanger assembly 64 is alsoarranged between the input coaxial waveguide section 14 and the outputcoaxial waveguide section 32. In certain embodiments, the heat exchangerassembly 64 forms a cylindrical shape that is configured to radiallysurround the center waveguide section 16, which also forms a cylindricalshape. As shown in FIG. 2, the heat exchanger assembly 64 may radiallyprotrude from the spatial power-combining device 10 when compared to theinput coaxial waveguide section 14 and the output coaxial waveguidesection 32. In this regard, the heat exchanger assembly 64 may beconfigured to provide increased surface area for heat dissipation ortransfer. In certain embodiments, the heat exchanger assembly 64comprises a highly thermally conductive material, such as Cu, Al, oralloys thereof. In addition to highly thermally conductive metals, theheat exchanger assembly 64 may comprise highly thermally conductivepolymers or ceramics, including graphite or graphene, or other highlythermally conductive materials. In certain embodiments, the heatexchanger assembly 64 may comprise the same material as the bodystructure (26 of FIG. 1) of each amplifier assembly (22 of FIG. 1). Inother embodiments, the heat exchanger assembly 64 comprises a differentmaterial than the body structure (26 of FIG. 1).

Accordingly to embodiments disclosed herein, heat exchanger assembliesmay include a heat transfer body and a cover structure that is attachedto the heat transfer body. A first face of the heat transfer body mayform a plurality of open passageways. When the cover structure isattached to the first face of the heat transfer body, the coverstructure is configured to enclose the open passageways to form aplurality of enclosed fluid conduits within a heat exchanger assembly.Forming the plurality of open passageways on the first face of the heattransfer body before enclosing the passageways allows improved thermalstructures for the plurality of enclosed fluid conduits. For example,the plurality of enclosed fluid conduits may be formed with differentdiameters, depths, different paths, and localized areas with increasedor decreased concentrations or densities within the heat exchangerassembly that would not otherwise be possible if fluid conduits areformed within a solid material. This allows the plurality of enclosedfluid conduits to be tailored to particular applications. For example,in spatial power-combining devices, heat exchanger assemblies may beconfigured with enclosed fluid conduits that are tailored to provideincreased localized cooling in the areas closest to the amplifiers.

FIG. 3 is a perspective view of a heat transfer body 66 according toembodiments disclosed herein. The heat transfer body 66 is illustratedwith a cylindrical shape in FIG. 3 that corresponds to the cylindricalshape of the center waveguide section (16 of FIG. 1). In otherembodiments, the heat transfer body 66 may have other shapes thatcorrespond to other shapes of electronic devices. The heat transfer body66 includes a first face 68 and a second face 70 that opposes the firstface 68. For the first face 68 to oppose the second face 70, at leastone additional surface, side, or face of the heat transfer body 66 isarranged between the first face 68 and the second face 70. Asillustrated in FIG. 3, for a cylindrically shaped heat transfer body 66,the first face 68 corresponds to an outer face of the heat transfer body66, and the second face 70 corresponds to an inner face of the heattransfer body 66 that is oriented toward a hollow center opening 72. Inthis regard, when fully assembled in the spatial combining device 10 ofFIG. 1, the center waveguide section (16 of FIG. 1) is arranged insidethe hollow center opening 72 and thermally coupled with the heattransfer body 66 by way of the second face 70. In certain embodiments,the heat transfer body 66 comprises a highly thermally conductivematerial, including various highly thermally conductive metals,polymers, or ceramics as previously described. The heat transfer body 66may comprise additional features configured to further improve heatdissipation or heat transfer. As illustrated in FIG. 3, the first face68 includes a plurality of open passageways 74-1 to 74-9, which may alsobe referred to as channels or trenches in the first face 68. In certainembodiments, the plurality of open passageways 74-1 to 74-9 aresubsequently enclosed by later described structures to form fluidconduits for cooling. In certain embodiments, the open passageways 74-1to 74-9 are configured differently in different areas of the first face68. For example, the passageway 74-1 is arranged radially on the firstface 68 and adjacent to a first edge 76 of the heat transfer body 66.Multiple passageways 74-2 extend from the passageway 74-1 in alongitudinal direction away from the first edge 76. Each of thepassageways 74-2 split into multiple passageways 74-3, which in turnsplit into multiple passageways 74-4. Pairs of the passageways 74-4combine into the passageways 74-5 that are centrally located on thefirst face 68. The passageways 74-6 to 74-8 may follow the sameprogression but in reverse toward the passageway 74-9 that is radiallyarranged on the first face 68 and adjacent to a second edge 78 of theheat transfer body 66. In this manner, the passageways 74-3 to 74-7 arearranged with increased densities or concentrations near a centralportion of the first face 68 that is between the first edge 76 and thesecond edge 78 of the heat transfer body 66.

In FIG. 3, the heat transfer body 66 forms a gap 80 that transversesfrom the first edge 76 to the second edge 78. In certain embodiments,the heat transfer body 66 is provided in a planar configuration that issubsequently formed into a final three-dimensional shape, such as thecylindrical shape illustrated in FIG. 3, and the gap 80 is therebyformed. In other embodiments, the gap 80 may not be present. Forexample, the heat transfer body 66 may initially be provided as a hollowtube and the plurality of open passageways 74-1 to 74-9 are formed on anouter surface of the hollow tube. By forming the plurality of openpassageways 74-1 to 74-9 on the first face 68 of the heat transfer body66 before enclosing the open passageways 74-1 to 74-9, improved thermalstructures may be provided that are tailored for specific applications.In certain embodiments, the open passageways 74-1 to 74-9 may be formedon the first face 68 of the heat transfer body 66 by an etching process.For example, the heat transfer body 66 may comprise Cu or Cu alloys incertain embodiments and a chemical etchant for Cu or Cu alloys, such asetchants containing cupric or copper chloride, ferric chloride, oralkaline etchants, among many others, may be used to form the openpassageways 74-1 to 74-9 on the first face 68. Specifically, thechemical etchant may by exposed to the first face 68 through a mask withpatterned openings that correspond to the open passageways 74-1 to 74-9.In this manner, the open passageways 74-1 to 74-9 may comprise virtuallyany pattern or arrangement on the first face 68 based on the mask. Thisallows complex and intricate patterns or arrangements of the openpassageways 74-1 to 74-9 to be tailored to the heat requirements of aparticular application. Specifically, the open passageways 74-1 to 74-9may be formed with variations across the first face 68 that correspondto localized areas of the heat transfer body 66 that experiencedifferent levels of heat during operation. In this manner, the openpassageways 74-1 to 74-9 may be more concentrated in certain areas ofthe heat transfer body 66, or certain passageways 74-1 to 74-9 may beconfigured with different depths or widths in localized areas of theheat transfer body 66. Chemical etching provides the ability to massproduce heat transfer bodies 66 as described above with reduced costsand repeatability, regardless of the complexity of the patterns of theopen passageways 74-1 to 74-9. In other embodiments, the openpassageways 74-1 to 74-9 may be formed by other techniques, includinglaser machining, rotary table machining, micromachining, multi-axismachining, water jet cutting, sandblasting, glass bead blasting,three-dimensional printing, molding, and injection molding depending onthe material of the heat transfer body 66.

FIG. 4 is a perspective view of a cover structure 82 that is configuredto cover the heat transfer body 66 of FIG. 3 according to embodimentsdisclosed herein. In certain embodiments, the cover structure 82comprises a shape that is configured in a similar manner to the firstface (68 of FIG. 3) of the heat transfer body (66 of FIG. 3). In thisregard, the cover structure 82 is illustrated with a cylindrical shapehaving an outer face 84 and an inner face 86, and the heat transfer body(66 of FIG. 3) may be thermally coupled to the cover structure 82 by wayof the inner face 86. The cover structure 82 may additionally includeone or more ports 88 that are configured to allow fluid flow through thecover structure 82. In certain embodiments, the cover structure 82comprises a highly thermally conductive material, such as Cu, Al, oralloys thereof. In addition to highly thermally conductive metals, thecover structure 82 may comprise highly thermally conductive polymers orceramics, including graphite or graphene, or other highly thermallyconductive materials. In certain embodiments, the cover structure 82 maycomprise the same material as the heat transfer body (66 of FIG. 3). Inother embodiments, the cover structure 82 may comprise a differentmaterial than the heat transfer body (66 of FIG. 3). For example, thecover structure 82 may comprise a material with lower thermalconductivity in embodiments where the heat transfer body (66 of FIG. 3)provides sufficient reduced operating temperatures. In certainembodiments, the cover structure 82 is provided in a planarconfiguration that is subsequently formed into a final three-dimensionalshape, such as the cylindrical shape illustrated in FIG. 4. Inthree-dimensional form, the cover structure 82 may form a gap 90. Inother embodiments, the gap 90 may not be present.

FIG. 5A is a perspective view of an assembled heat exchanger assembly 64that includes the heat transfer body 66 of FIG. 3 and the coverstructure 82 of FIG. 4. As illustrated, the cover structure 82 isattached to cover or enclose the first face (68 of FIG. 3) of the heattransfer body 66. In certain embodiments, the cover structure 82 may besoldered, brazed, welded, bonded with epoxy, or otherwise bonded to theheat transfer body 66. In other embodiments, the cover structure 82 maybe mechanically attached by screws or the like to the heat transfer body66. When present, the gap 80 of the heat transfer body 66 may beconfigured in alignment with the gap 90 of the cover structure 82. Theone or more ports 88 in the cover structure 82 as previously describedmay be provided to allow fluid flow into and out of the heat exchangerassembly 64. FIG. 5B is a perspective view of the heat exchangerassembly 64 of FIG. 5A with the cover structure 82 shown as transparentfor illustrative purposes. When the cover structure 82 is attached tothe first face 68 of the heat transfer body 66, the plurality of openpassageways (74-1 to 74-9 of FIG. 3) are enclosed to form a plurality ofenclosed fluid conduits 92-1 to 92-9. In particular, the cover structure82 may be configured to attach, contact, or bond with areas of the firstface 68 that are between individual open passageways of the plurality ofopen passageways (74-1 to 74-9 of FIG. 3), thereby enclosing and sealingthe plurality of open passageways (74-1 to 74-9 of FIG. 3) to form theenclosed fluid conduits 92-1 to 92-9. Fluid, such as a cooling liquid ora cooling gas, may be provided into and out of the heat exchangerassembly 64 by way of the one or more ports 88. In certain embodiments,at least one port 88 is registered with at least one fluid conduit 92-9and another port, which is obscured from view in the illustration ofFIG. 5B, may be registered with a different fluid conduit 92-1. In thismanner, fluid may be provided to flow into the heat exchanger assembly64 and transverse the heat exchanger assembly 64 within the enclosedfluid conduits 92-1 to 92-9, before exiting the heat exchanger assembly64, thereby providing improved heat dissipation or heat transfer. Incertain embodiments, the cover structure 82 may be attached to the heattransfer body 66 with one or more gaskets or o-rings that are configuredto seal the enclosed fluid conduits 92-1 to 92-9.

In certain embodiments, the enclosed fluid conduits 92-1 to 92-9 arearranged with variations across the first face 68 that correspond tolocalized areas of the heat exchanger assembly 64 that experiencedifferent levels of heat during operation as previously described. Inthis manner, the enclosed fluid conduits 92-1 to 92-9 may be moreconcentrated in certain areas of the heat exchanger assembly 64, orcertain fluid conduits 92-1 to 92-9 may be configured with differentdimensions such as different diameters in localized areas of the heatexchanger assembly 64. For a spatial power-combining device, the fluidconduits 92-1 to 92-9 may be more concentrated in areas of the heatexchanger assembly 64 that correspond to the location of the amplifiers.As illustrated in FIG. 1, the amplifiers (52 of FIG. 1) may be centrallylocated within the center waveguide section (16 of FIG. 1). Accordingly,the fluid conduits 92-1 to 92-9 may be more concentrated in centralportions of the heat exchanger assembly 64 than in portions that arecloser to peripheral edges of the heat exchanger assembly 64. Localizedareas of the heat exchanger assembly 64 with higher concentrations ofthe fluid conduits 92-1 to 92-9 allow an increased amount of fluid inthe localized areas, thereby increasing cooling capabilities. In certainembodiments, certain fluid conduits 92-3 to 92-7 may have smallerdiameters than other fluid conduits 92-1, 92-2, 92-8, and 92-9. Smallerdiameters may promote increased velocity and/or turbulent fluid flow forfluid traversing in certain areas of the heat exchanger assembly 64,thereby providing improved heat transfer and reduced operatingtemperatures in such areas. In this manner, localized areas of the heatexchanger assembly 64 that experience the highest operating temperaturesmay be configured to have the highest velocities of fluid flow. In otherembodiments, the enclosed fluid conduits 92-1 to 92-9 may be configuredwith larger diameters in areas that experience the highest operatingtemperatures. In this regard, an increased quantity of fluid may beprovided in the hottest areas of the heat exchanger assembly 64. Asillustrated in FIG. 5B, the certain fluid conduits 92-3, 92-4, 92-6,92-7 may include one or more curved portions. For example, the fluidconduit 92-3 comprises alternating concave and convex curved portionsbetween the fluid conduit 92-2 and the fluid conduit 92-4. In thisregard, fluid may flow across an increased area of the heat exchangerassembly 64 between the fluid conduit 92-2 and the fluid conduit 92-4.In a similar manner, the fluid conduit 92-4 comprises alternatingconcave and convex curved portions between the fluid conduit 92-3 andthe fluid conduit 92-5; however, the curved portions of the fluidconduit 92-4 have smaller dimensions than the curved portions of thefluid conduit 92-3. Accordingly, the pattern of the fluid conduit 92-4may be repeated radially around certain portions of the heat exchangerassembly 64 with closer spacing than the pattern of the fluid conduit92-3, thereby providing increased fluid flow in such portions of theheat exchanger assembly 64. The plurality of enclosed fluid conduits92-1 to 92-9 may comprise other features that provide localized areaswith increased heat transfer. For example, certain fluid conduits mayinclude increased surface roughness on surfaces inside the fluidconduits. In other examples, certain fluid conduits may compriseprotruding features within the fluid conduits, such as micro finstructures or other shapes. In still other examples, certain fluidconduits may comprise transitions in shape, such as a fluid conduit thattransitions from a round cross-section into a square-shapedcross-section. In certain embodiments, the heat exchanger assembly 64may be held in place to the center waveguide section (16 of FIG. 1) by aclamp or other mechanical fastener.

As previously described, by forming open passageways on a face of heattransfer body before enclosing the open passageways, improved thermalstructures may be provided that are tailored for specific applications.In this manner, a method of manufacturing a heat exchanger assemblyincludes forming open passageways on a face of a heat transfer body andsubsequently enclosing the open passageways with a cover structure. In afirst step, a heat transfer body may be provided as a flat or planarsheet of material. Open passageways are then formed by selectivelyremoving material from a face of the heat transfer body. Selectiveremoval may include chemical etching, laser machining, rotary tablemachining, micromachining, and multi-axis machining. Forming the openingpassageways and subsequently enclosing the open passageways to formfluid conduits provides the ability to mass produce heat transfer bodiesas described above with reduced costs and repeatability, regardless ofthe complexity of the patterns of the open passageways. In certainembodiments, multiple heat transfer bodies may be formed simultaneouslyby providing multiple groups of open passageways across a larger area ofa heat transfer body material, and subsequently singulating the heattransfer body material into multiple heat transfer bodies. Coverstructures as previously described may be formed on the heat transferbodies before or after singulation.

FIG. 6 is top view of a heat transfer body material 94 on which aplurality of heat transfer bodies 96-1 to 96-6 will be formed onaccording to embodiments disclosed herein. In FIG. 6, the heat transferbody material 94 is provided as a planar sheet of material that maycomprise highly thermally conductive metals such as Cu, Al, or alloysthereof, or highly thermally conductive polymers or ceramics aspreviously described. In a first step, a plurality of open passagewaypatterns 98-1 to 98-6 are formed on a first face 99 of the heat transferbody material 94 to at least partially define regions where theplurality of heat transfer bodies 96-1 to 96-6 will be formed. A secondface of the heat transfer body material 94 that opposes the first face99 is obscured from the top view of FIG. 6. Each of the plurality ofopen passageway patterns 98-1 to 98-6 may include a plurality of openpassageways as previously described. The plurality of open passagewaypatterns 98-1 to 98-6 may be formed by a selective removal process aspreviously described, including chemical etching, laser machining,rotary table machining, micromachining, multi-axis machining, water jetcutting, sandblasting, glass bead blasting, three-dimensional printing,molding, and injection molding. Singulation lines 100, which may also bereferred to as dicing lines or streets, are shown in dashed lines toindicate the areas of the heat transfer body material 94 whereindividual heat transfer bodies 96-1 to 96-6 will be separated from oneanother. In certain embodiments, the heat transfer bodies 96-1 to 96-6will be separated from one another in later processing steps. In otherembodiments, the heat transfer bodies 96-1 to 96-6 may be separated fromone another before subsequent processing steps.

FIG. 7 is a top view illustrating formation of cover structures 102-1 to102-6 over the heat transfer body material 94 of FIG. 6. Each of thecover structures 102-1 to 102-6 are registered with a different one ofthe plurality of heat transfer bodies (96-1 to 96-6 of FIG. 6) to form aplurality of heat exchanger assemblies 104-1 to 104-6 as previouslydescribed. In certain embodiments, the cover structures 102-1 to 102-6are formed as a single sheet of cover structure material that isattached to the heat transfer body material (94 of FIG. 6). Theattachment step may include soldering, brazing, welding, bonding withepoxy, or other bonded techniques, or mechanical attachment to seal theplurality of open passageway patterns (98-1 to 98-6 of FIG. 6) aspreviously described. The one or more ports 88 as previously describedmay be formed in the cover structures 102-1 to 102-6 before or after theattachment step. As with FIG. 6, the singulation lines 100 are shown indashed lines. In certain embodiments, the singulation or separation stepmay comprise conventional machining, laser machining, water jet cutting,mechanical sawing, laser dicing, scribing and breaking, among othersingulation or separation techniques. After separation along thesingulation lines 100, the plurality of heat exchanger assemblies 104-1to 104-6 are separated from one another.

FIG. 8A is a top view of an individual heat exchanger assembly 104-1 ofFIG. 7 after singulation. The heat exchanger assembly 104-1 is providedin planar form with the one or more ports 88 as previously described. Inthe top view of FIG. 8A, only the cover structure 102-1 and the one ormore ports 88 are visible. FIG. 8B is a top view of the heat exchangerassembly 104-1 with the cover structure 102-1 shown as transparent forillustrative purposes. When the cover structure 102-1 is attached to theheat transfer body 96-1, the open passageway pattern 98-1, which mayinclude a plurality of open passageways, is enclosed to form enclosedfluid conduits 92-1 to 92-9 as previously described. Fluid, such as acooling liquid or a cooling gas, may be provided into and out of theheat exchanger assembly 104-1 by way of the one or more ports 88. Forexample, fluid may enter the port 88 that is registered with theenclosed fluid conduit 92-1 and flow through the enclosed fluid conduits92-2 to 92-9, before exiting through the port 88 that is registered withthe fluid conduit 92-9. In this manner, after separation or singulation,the individual heat exchanger assembly 104-1 includes the heat transferbody 96-1, the cover structure 102-1, and the plurality of enclosedfluid conduits 92-1 to 92-9. In other embodiments, the cover structure102-1 may be attached to the heat transfer body 96-1 after the heattransfer body 96-1 has been singulated or separated from the heattransfer body material (94 of FIG. 6). In this manner, the coverstructure 102-1 is separately attached to the heat transfer body 96-1 toform the heat exchanger assembly 104-1.

In certain embodiments, the heat exchanger assembly 104-1 may bearranged along a planar portion of an electronic device to provide heattransfer and dissipation. In other embodiments, the heat exchangerassembly 104-1 may be formed into a non-planar shape that is configuredto provide heat transfer and dissipation for a non-planar electronicsdevice. For example, the heat exchanger assembly 104-1 may be formedinto a cylindrical shape as illustrated in FIG. 5B to provide thermalmanagement to a spatial power-combining device as previously described.The heat exchanger assembly 104-1 may be formed into non-planar shapesby sheet metal bending equipment, or by bending or otherwise forming theheat exchanger assembly 104-1 around a non-planar template, such as acylindrical rod with a diameter configured to approximate the centerwaveguide section of a spatial power-combining device, or by any othermeans to obtain a desired non-planar shape.

FIG. 9A is a top view of a heat transfer body 106 with a differentconfiguration of a plurality of open passageways 108-1 to 108-7according to embodiments disclosed herein. In FIG. 9A, the plurality ofopen passageways 108-1 to 108-7 are configured to divide and subdividemultiple times from a first edge 110 and a second edge 112 of the heattransfer body 106 to a central portion of the heat transfer body 106.For example, the passageway 108-1 is arranged on a first face 114 of theheat transfer body 106 and adjacent to the first edge 110 in alengthwise manner. Multiple passageways 108-2 extend from the passageway108-1 in a direction away from the first edge 110. Each passageway 108-2is then configured to split into multiple passageways 108-3, and inturn, split into even more passageways 108-4 that are centrally locatedbetween the first edge 110 and the second edge 112. The pattern repeatsitself in reverse from the passageways 108-4 to the passageway 108-7that is adjacent to the second edge 112. A cover structure may beattached to the first face 114 to form a heat exchanger assembly aspreviously described. In certain embodiments, the heat transfer body 106may comprise a substantially planar shape or a planar sheet and maythereby be configured to provide thermal management to a planar portionof an electronic device. In other embodiments, the heat transfer body106 may subsequently be formed into a non-planar shape to providethermal management to a non-planar electronic device.

FIG. 9B is a perspective view of the heat transfer body 106 of FIG. 9Athat has been formed into a non-planar shape. In FIG. 9B, the heattransfer body 106 has been formed into a cylindrical shape as previouslydescribed. In this manner, the heat transfer body 106 includes the firstface 114, a second face 116 that is opposite the first face 114, ahollow center opening 118, and a gap 120 as previously described. Whenenclosed by a cover structure as previously described, the passageways108-1 to 108-7 thereby provide fluid conduits that have a highestconcentration along a central radial area between the first and secondedges 110, 112, where the highest concentration of fluid conduits isregistered with the passageways 108-4 of the heat transfer body 106. Inother embodiments, other areas of the heat transfer body 106 may beconfigured with the highest concentration of the passageways 108-1 to108-7 corresponding to different portions of the heat transfer body 106that may experience higher operating temperatures. As illustrated inFIGS. 9A and 9B, the passageways 108-1 to 108-7 are configured to dividein a linear manner.

FIG. 10A is a perspective view of a heat transfer body 122 with adifferent configuration of a plurality of open passageways 124-1 to124-3 according to embodiments disclosed herein. In FIG. 10A, thepassageway 124-1 is arranged on a first face 126 of the heat transferbody 122 and adjacent to a first edge 128 in a lengthwise manner.Multiple passageways 124-2 extend from the passageway 124-1 in a linearmanner to the passageway 124-3 that is arranged adjacent to a secondedge 130 of the heat transfer body 122. When enclosed by a coverstructure as previously described, the passageways 124-1 to 124-3thereby provide a plurality of linear fluid conduits that transverse theheat transfer body 122 in a linear manner from the first edge 128 to thesecond edge 130 of the of the heat transfer body 122. A cover structuremay be attached to the first face 126 to form a heat exchanger assemblyas previously described. In certain embodiments, the heat transfer body122 may comprise a substantially planar shape or a planar sheet and maythereby be configured to provide thermal management to a planar portionof an electronic device. In other embodiments, the heat transfer body122 may subsequently be formed into a non-planar shape to providethermal management to a non-planar electronic device.

FIG. 10B is a perspective view of the heat transfer body 122 of FIG. 10Athat has been formed into a non-planar shape. In FIG. 10B, the heattransfer body 122 has been formed into a cylindrical shape as previouslydescribed. In this manner, the heat transfer body 122 includes the firstface 126, a second face 132 that is opposite the first face 126, ahollow center opening 134, and a gap 136 as previously described. Whenenclosed as previously described, the passageways 124-1 to 124-3 therebyprovide a plurality of linear fluid conduits that transverse the heattransfer body 122 in a linear manner between two radially arranged fluidconduits that are arranged adjacent to the first and second edges 128,130 of the of the heat transfer body 122.

Those skilled in the art will recognize improvements and modificationsto the preferred embodiments of the present disclosure. All suchimprovements and modifications are considered within the scope of theconcepts disclosed herein and the claims that follow.

What is claimed is:
 1. A method for fabricating a heat exchangerassembly for a spatial power-combing device, the method comprising:providing a heat transfer body comprising a first face and a second facethat opposes the first face; forming a plurality of open passageways onthe first face; and attaching a cover structure to the first face toform the heat exchanger assembly, wherein the cover structure and theplurality of open passageways of the heat transfer body form a pluralityof enclosed fluid conduits within the heat exchanger assembly, andforming the heat exchanger assembly into a cylindrical shape.
 2. Themethod of claim 1, wherein forming the plurality of open passageways onthe first face comprises selectively removing portions of the heattransfer body on the first face.
 3. The method of claim 2, whereinselectively removing portions of the heat transfer body on the firstface comprises at least one of chemical etching, laser machining, rotarytable machining, micromachining, multi-axis machining, water jetcutting, sandblasting, glass bead blasting, three-dimensional printing,molding, and injection molding.
 4. The method of claim 2, whereinselectively removing portions of the heat transfer body on the firstface comprises applying a chemical etchant through a mask on the firstface.
 5. The method of claim 1, wherein attaching the cover structure tothe first face comprises at least one of soldering, brazing, welding, orbonding with epoxy.
 6. The method of claim 1, wherein the heat exchangerassembly comprises a planar shape.
 7. The method of claim 1, furthercomprising forming the heat exchanger assembly into a non-planar shape.8. The method of claim 7, wherein the non-planar shape comprises acylindrical shape.
 9. The method of claim 7, wherein the cover structureis attached to the first face before forming the heat exchanger assemblyinto the non-planar shape.
 10. The method of claim 1, wherein theplurality of enclosed fluid conduits are arranged in differentconcentrations within different areas of the heat exchanger assembly.11. The method of claim 1, wherein at least one enclosed fluid conduitof the plurality of enclosed fluid conduits is arranged with a differentdiameter than other enclosed fluid conduits of the plurality of enclosedfluid conduits.
 12. The method of claim 1, wherein at least one enclosedfluid conduit of the plurality of enclosed fluid conduits comprisesalternating concave and convex curved portions.
 13. The method of claim1, wherein at least one enclosed fluid conduit of the plurality ofenclosed fluid conduits is configured to split into multiple enclosedfluid conduits between a first edge and a second edge of the heattransfer body.
 14. The method of claim 1, wherein at least one enclosedfluid conduit of the plurality of enclosed fluid conduits transversesthe heat exchanger assembly in a linear manner between two radiallyarranged enclosed fluid conduits of the plurality of enclosed fluidconduits.
 15. A method comprising: providing a heat transfer bodymaterial; forming a plurality of open passageway patterns on a firstface of the heat transfer body material; attaching a cover structurematerial to the first face, wherein the cover structure material and theplurality of open passageway patterns form a plurality of enclosed fluidconduits; separating the heat transfer body material and the coverstructure material into a plurality of heat exchanger assemblies,wherein each heat exchanger assembly of the plurality of heat exchangerassemblies comprises a heat transfer body, a cover structure, and aplurality of enclosed fluid conduits; and forming each heat exchangerassembly of the plurality of heat exchanger assemblies into acylindrical shape.
 16. The method of claim 15, wherein forming theplurality of open passageway patterns on the first face comprisesselectively removing portions of the heat transfer body material on thefirst face.
 17. The method of claim 16, wherein selectively removingportions of the heat transfer body material on the first face comprisesat least one of chemical etching, laser machining, rotary tablemachining, micromachining, or multi-axis machining.
 18. The method ofclaim 16, wherein selectively removing portions of the heat transferbody material on the first face comprises applying a chemical etchantthrough a mask on the first face.
 19. A method for fabricating a heatexchanger assembly for a spatial power-combing device, the methodcomprising: providing a heat transfer body comprising a first face and asecond face that opposes the first face; forming a plurality of openpassageways on the first face; attaching a cover structure to the firstface to form the heat exchanger assembly, wherein the cover structureand the plurality of open passageways of the heat transfer body form aplurality of enclosed fluid conduits within the heat exchanger assembly;and forming the heat exchanger assembly into a cylindrical shape. 20.The method of claim 19, wherein forming the plurality of openpassageways on the first face comprises selectively removing portions ofthe heat transfer body on the first face.
 21. The method of claim 20,wherein selectively removing portions of the heat transfer body on thefirst face comprises at least one of chemical etching, laser machining,rotary table machining, micromachining, multi-axis machining, water jetcutting, sandblasting, glass bead blasting, three-dimensional printing,molding, and injection molding.
 22. The method of claim 20, whereinselectively removing portions of the heat transfer body on the firstface comprises applying a chemical etchant through a mask on the firstface.
 23. The method of claim 19, wherein the cover structure isattached to the first face before forming the heat exchanger assemblyinto the cylindrical shape.
 24. The method of claim 19, wherein at leastone enclosed fluid conduit of the plurality of enclosed fluid conduitstransverses the heat exchanger assembly in a linear manner between tworadially arranged enclosed fluid conduits of the plurality of enclosedfluid conduits.